If Threatfire is 'real-time', wouldn't that interfere with avast? This is just an issue I'd like to clarify before I rush into downloading anything.
There was a reported issue with TF after their upgrade about 1- 2 months ago. So you may want to look into this prior to installing, or look into another product. I've had no problems with PrevX (resident cloud/behavior) and Avast for the past 1.5 years and any upgrades.
In addition, there are other firewalls that play well with Avast, such as Online Armor, PC ToolsPlus, Comodo, OutPost.
As for a cleaner, many of us here use CCleaner
http://www.piriform.com/ccleaner is a freeware system optimization, privacy and cleaning tool. There is a Slim version available as well at
http://www.piriform.com/ccleaner/builds. It removes unused files (cache, temporary Internet files, etc.) from your system - allowing Windows to run faster and freeing up valuable hard disk space. It also cleans traces of your online activities such as your Internet history. Additionally it contains a fully featured registry cleaner. Remember
when installing to uncheck the Yahoo toolbar.
Take a look at user's Signatures (at the bottom of our posts) to get an idea of what people use. And welcome to the forum.